Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

@"
"
gmi

Test String

Code Generator

Language

Generated Code

const regex = new RegExp('(?<timestamp_utc>\\d\\d\\d\\d\\-\\d\\d\\-\\d\\d\\s\\d\\d\\:\\d\\d\\:\\d\\d)\\s[^\\s]+\\sPOST\\s\\/RDWeb\\/Pages\\/[^\\/]+\\/login\\.aspx\\s[^\\s]+\\s[0-9]+\\s-\\s(?<ipaddress>[^\\s]+).*\\s200\\s[^\\n]+\\n', 'gmi') const str = `2023-03-20 05:43:20 1.2.3.4 POST /RDWeb/Pages/en-US/login.aspx - 443 - 2.3.4.5 Mozilla/5.0+(Macintosh;+Intel+Mac+OS+X+10_15_7)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/109.0.0.0+Safari/537.36 https://your.rdsserver.org.uk/RDWeb/webclient/ 200 0 0 15 2023-03-20 15:33:46 1.2.3.4 POST /RDWeb/Pages/en-US/login.aspx ReturnUrl=%2FRDWeb%2FPages%2Fen-US%2FDefault.aspx 443 - 2.3.4.5 Mozilla/5.0+(Windows+NT+10.0;+Win64;+x64)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/111.0.0.0+Safari/537.36 https://your.rdsserver.org.uk/RDWeb/Pages/en-US/login.aspx?ReturnUrl=/RDWeb/Pages/en-US/Default.aspx 200 0 0 2265 2024-03-15 00:04:49 1.2.3.4 POST /RDWeb/Pages/en-US/login.aspx - 443 - 36.133.118.254 node-fetch/1.0+(+https://github.com/bitinn/node-fetch) - 200 0 0 763 2024-03-21 02:47:46 1.2.3.4 POST /RDWeb/Pages/en-US/login.aspx - 443 - 41.185.8.146 - - 200 0 0 391 `; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions